Electrically actuated demolition device



April 1, 1969 w. B. CUNNINGHAM 3,436,121

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ATTORNEY April 1, 1969 w. B. CUNNINGHAM 3,436,121

ELECTRICALLY ACTUATED DEMOLITION DEVICE Filed May 2, 1967 Sheet 3 7 k oucelz l .5 3 /.37

{717% INVENTOR ATTORNEY United States Patent 3,436,121 ELECTRICALLY ACTUATED DEMOLITION DEVICE Wesley B. 'Cunningham, 2 Morris St., Charleston, W. Va. 25301 Filed May 2, 1967, Ser. No. 635,596 Int. Cl. E21b 1/00 US. Cl. 299-70 6 Claims ABSTRACT OF THE DISCLOSURE tending slidably through the bottom of the casing and provided on its bottom end with a striking head. The plunger is biased upwardly by a coiled spring in the lower end of the casing, surrounding the shaft. A solenoid winding is mounted on the lower end of the casing in a position to exert magnetic attraction on the plunger and to drive it downwardly when the solenoid winding is energized, causing the striking head to deliver an impact therebeneath. Another coiled spring is mounted between the top end of the plunger and the top wall of the casing to cushion upward return of the plunger when the solenoid winding is deenergized. A switch-controlled energizing circuit is connected to the solenoid winding.

This invention relates to demolition devices of the type mounted on mobile construction equipment, and more particularly to an electrically operated impact-imparting tool for use on mobile construction equipment and employed for clearing construction sites, disintegrating pavement, crushing roadway obstacles, and the like.

A main object of the invention is to provide a novel and improved demolition tool mounted on construction equipment of the type provided with a swinging boom, the tool being relatively simple in construction, being electrically operated, and providing powerful striking force by electromagnetic action, the tool being adapted for use as an impact-imparting implement for disintegrating ground level materials, such as existing pavements and roadbeds, and being equally adapted for destroying or disintegrating walls and other upstanding objects.

A further object of the invention is to provide an improved demolition device mounted on mobile apparatus readily transported to various locations and being useable at varying angles with respect to the vehicle on which it is mounted.

A still further object of the invention is to provide an improved electrically operated demolition tool mounted on a construction vehicle or the like, which is versatile in performance, which provides powerful and effective impact, which can be energized from a power source which is remotely located relative to the demolition device, and which can be controlled safely and efficiently.

A still further object of the invention is to provide an improved portable demolition tool which is easy to manoeuvre, which is smooth in operation, and which involves a minimum number of working parts.

Further objects and advantages of the invention will become apparent from the following description and claims,.and from the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of a portion of a typical construction machinery unit provided with an improved electrically operated demolition device constructed in accordance with the present invention, shown in striking position.

FIGURE 2 is an enlarged vertical cross-sectional view taken substantially on the line 22 of FIGURE 1, with the device in its normal deenergized position.

FIGURE 3 is a horizontal cross-sectional view taken substantially on line 33 of FIGURE 2.

FIGURE 4 is a wiring diagram showing the electrical connections of a typical demolition device such as that illustrated in FIGURES l to 3.

FIGURE 5 is a wiring diagram showing a modified form of electrical circuit for a demolition device according to the present invention.

FIGURE 6 is a diagrammatic view showing a demolition device according to the present invention employed in a horizontal position and suspended from a power crane to demolish a masonry wall.

Referring to the drawings, 10 generally designates an electrically operated demolition device according to the present invention, said device being shown mounted on a typical unit of construction machinery 12. The machinery 12 may be of any suitable type, and preferably includes a prime mover (not shown), provided with an outward boom 14 whose position is controlled by a first hydraulic cylinder 15, and having a pivotally mounted end boom 16 thereon. A second hydraulic cylinder assembly 18 is employed to pivot the end boom 16 with respect to the boom 14. A work element, such as a scoop 20, is pivoted on the distal end of the boom 16, and a third hydraulic cylinder assembly 22 operates the same. The third cylinder assembly 22 includes a cylinder 2'4 connected to the prime mover power source, and an extensible element 26 secured to the scoop 20, whereby extension and retraction of the element 26 pivots the scoop about the distal end of boom 16.

The demolition device 10 comprises an elongated tubular casing 28 of suitable non-magnetic material, such as aluminum or strainless steel, having the top wall 29 and the centrally apertured bottom wall 30. The top portion of casing 28 is rigidly secured, as by a bracket 25, to the upper portion 27 of end boom 16. Slidably mounted in the upper portion of casing 28 is a plunger 31 of magnetic material, such as steel. A shaft member 32 of suitable nonmagnetic material, such as aluminum or stainless steel, extends slidably through the central aperture of bottom wall 30, the top end of the shaft member being formed with the reduced threaded stud portion 33 which is threadedly secured in the bottom end of the magnetic plunger 31. A coiled spring 34 of non-magnetic material, such as stainless steel or non-ferrous alloy, surrounds shaft 32, bearing between bottom wall 30 and the bottom end of plunger 31, as shown in FIGURE 2, biasing the shaft 32 upwardly toward the position shown. An enlarged striking head 35 is provided on the bottom end of shaft 32.

Surrounding and secured on the lower end portion of casing 28 is a solenoid winding 36 contained in a nonmagnetic shell 37 of aluminum, stainless steel, or any other suitable non-magnetic material. The bottom wall 38 of shell 27 is secured to the bottom wall 30 of casing 28 and has a central aperture registering with the central aperture of bottom wall 30 to allow shaft 32 to pass slidably therethrough.

The top end of plunger 31 is formed with an axial recess 39 of substantial depth receiving and supporting the lower portion of a coiled spring 40 of non-magnetic material. The top end of spring 40 bears against top wall 29. Spring 40 serves to cushion the upward movement of plunger 31 caused by the expansion of the substantially heavier main spring 34, as will be presently described.

The terminal wires 41 and 42 of the solenoid winding 36 are electrically connected to a suitable electrical power source, such as a generator 43, through a manually operated control switch 44. The electrical power source may also comprise a suitable battery.

The control switch 44 may be mounted in any convenient location, such as on the instrument panel of the associated vehicle or mobile machine. The power source 43 may be located either on the vehicle or machine, or may be at a remote location relative to the demolition device 10, with suitable transmission conductors connecting it to the wires 41 and 42 through the control switch 44.

It will be understood that the switch 44 may be either operated by direct manual means or may be relay-controlled if so desired.

In operation, the demolition device is suitably oriented relative to the material or object to be disintegrated, :by operating the respective boom-controlling cylinders and 18 to suitably position the main boom 14 and the end boom 16 to place the striking head 35 in striking position opposite the material to be demolished. For example, the demolition device 10 may be oriented vertically, as in FIGURE 1, to crush material immediately below, such as a pavement or roadbed. Switch 44 is then momentarily closed, causing solenoid winding 36 to be energized and to exert a substantial downward magnetic force on the plunger 31. The solenoid draws sufiicient current and has a sufiicient number of turns to develop a magnetomotive force which greatly exceeds the upward biasing force of spring 34, whereby to drive the shaft 32 downwardly and to cause the striking head 35, which has considerable mass, to deliver the required demolition impact to the material engaged thereby. Upon opening the switch 44, the solenoid winding 36 becomes deenergized, allowing the spring 34 to expand and to rapidly elevate the plunger 31 towards its star-ting position in the upper portion of casing 28. The upward momentum of the plunger 31 and the parts carried thereby, namely, shaft 32 and head 35, is absorbed by the buffer spring 40, preventing impact against top wall 29, and providing smooth and quiet return of the plunger and shaft to their starting positions.

The coiled spring 34 is preferably only stitl enough to promptly return the plunger 31 to its starting position for repeated operation after an impact.

FIGURE 5 shows a modified arrangement in which the demolition device 10 is cyclically energized, whereby to provide periodically repeated impacts. As in FIGURE 4, the wire 41 is connected to one output terminal of generator 43. The wire 42 is connected to the remaining output terminal wire 50 of the generator through a rotary switch 51 having a rotating contact arm 52 and astationary contact 53. Arm 52 is driven through a suitable speed reducer 54 by an electric motor 55. One terminal of motor 55 is connected by a wire 56 to the generator output terminal wire 41 and the other terminal of motor 55 is connected by a wire 57 and the manual control switch 44 to the remaining generator output terminal wire 50. When switch 44 is closed, motor 55 becomes energized and causes arm 52 to rotate. This causes arm 52 to periodically engage contact 53, whereby the solenoid winding of the demolition device 10 is energized periodically at the rate of rotation of arm 52, causing the demolition device to deliver repeated impacts at the same rate.

FIGURE 6 illustrates how a demolition device 19 can be suspended from the boom 61 of a conventional power crane 60, with the demolition device supported by cables 62, 63 so as to operate in a horizontal position, for example, to deliver impacts to a high masonry wall 64 for the purpose of demolishing same. The height of the demolition device 10 can be adjusted as required by operating the controls of the crane 60 to lower or raise the cable 62, as required, and to correspondingly adjust the boom-supporting elements of the crane. The solenoid winding 36 of the demolition device 10 is energized by wires in a flexible cable 66, leading to a generator or other current source carried in the cab 67 of the crane, and the control switch and other control elements associated with the operation of the demolition device 10 are likewise located in the crane cab 67. The demolition device 10 is of relatively heavy construction and has considerable mass, enabling correspondingly heavy impacts to be delivered to the masonry wall 64 or other stationary structure to be demolished.

While certain specific embodiments of an improved electrically operated demolition device for mobile equipment has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. An impact imparting device adaptable for attachment to mobile construction equipment or the like, said impact imparting device comprising: an elongated hollow tubular housing formed of high strength, non-magnetic metal and having a closed upper end and an apertured lower end, a solenoid winding concentrically mounted on the outside of said tubular housing at one end thereof, an impact member of a length generally on the order of said tubular housing carried internally thereof for reciprocable movement therein, said impact member including a magnetic material portion and a non-magnetic portion extending partially through said lower apertured end, spring means carried by said housing and engaging said impact member to bias said magnetic portion into an extended position with respect to said solenoid winding, and an energizing circuit connected to said solenoid winding and including a control switch for selectively repositioning said magnetic material portion into axial alignment with said solenoid winding upon energization of said solenoid, against the biasing force of said spring means.

2. The impact imparting device of claim 1 wherein said impact member comprises two axially joined sections, a first section of magnetic material of a length corresponding to the length of said hollow tubular housing which extends beyond said solenoid winding, and a second section of high strength, non-magnetic metal which passes through said solenoid winding in the absence of coil energization with its terminal end extending through said lower apertured housing end.

3. The impact imparting device as claimed in claim 2 wherein said second non-magnetic metal material section of said impact member is of a lesser diameter than said magnetic material section and wherein said spring bias means comprises a coil spring cairried concentrically of said second section with one end abutting the inner end of said magnetic portion section at the point of coupling between said sections.

4. The impact imparting device of claim 3 further including a central recess carried on the outer end of said first magnetic material section of said impact member, and a second coil spring of reduced spring constant carried by said impact imparting device positioned within the recessed end of said magnetic portion section of said impact member and in contact with the closed upper end of said tubular casing.

5. The impact imparting device as claimed in claim 4 wherein said energizing circuit comprises a source of voltage, and said control switch comprises a cyclically operated switch member for sequentially closing the circuit between said solenoid winding and said voltage source.

6. The impact imparting device as claimed in claim 5 wherein said voltage source comprises a generator, and said rotary control switch comprises an electric motor driven by said generator and speed reducer means coupling the output shaft of said motor to said rotary switch 5 6 to control the cyclic delivery of current to said solenoid 545,149 8/1895 Carpenter 1731 17 X winding. 1,341,944 6/1920 Study 173117 References Cited UNITED STATES PATENTS ERNEST R. PURSER, Pillfldl y Examzner.

235,948 12/1880 Holcombe et a1. 173117 X 5 US. Cl. X.R.

508,262 11/1893 Williams 173-117 X 173-117 

